International multilingual mailbox electronic email, or simply multilingual email, refers to emails that use international multilingual mailboxes. International multilingual mailbox, also known as an international email address, refers to an email address that contains Chinese, Japanese and other non-English characters, such as “, ”. RFC6531 and RFC6532 technology standards issued by IETF in 2012 specify the technical standards for international multilingual mailbox emails.
Currently there is a coexistence of systems that support the technical standards of international multilingual mailbox emails and systems that do not support those technical standards. Sending and receiving email messages between these two types of systems are still an unresolved problem.